Bioreactors are commonly used for large-scale cell culture. Non-adherent cells can be cultured in suspension. However, adherent cells are provided an attachment surface in order to maintain basic functions such as cell-cell signaling, growth, and proliferation. The topography of the attachment surface can influence morphology and function, and some adherent cells display a preference for textured surfaces. Extracellular matrix (ECM) components are produced and secreted by the cells to anchor the cells to the surface and to one another. As surface texture increases the total surface area available for ECM anchorage, adherent cells may adhere more firmly to textured attachment surfaces than to smooth surfaces.
Typically, a small number of adherent cells are added to a liquid growth medium and placed in a vessel with the attachment surface. The cells adhere to the attachment surface and proliferate, gradually spreading in a monolayer or multi-layer structure across the available surface. If the cells are not removed, contact inhibition disrupts the cell growth cycle. Therefore, in order to obtain viable cells, the cells are generally removed from the attachment surface through immersion in a removal solution. Removal solutions typically include one or more proteolytic enzymes, such as trypsin, and/or a metal ion chelator, such as EDTA. The removal solution cleaves ECM components and sequesters calcium ions, disrupting the cell-cell and cell-surface bonds. The adherent cells are released from the surface and from neighboring cells, and are then washed and collected by various recovery techniques.